In minimally-invasive surgery, so-called telemanipulator systems, also referred to as robot-assistance systems or generally as apparatus for robot-assisted surgery, are increasingly used. By means of an apparatus for robot-assisted surgery, surgical instruments are controlled in their position and orientation on the basis of user inputs. The surgical instruments are further mechanically, electrically and/or optically coupled to the telemanipulator system so as to be able to implement an active positioning and orientation of the surgical instrument as well as a desired actuation of a surgical instrument. For this, the surgical instruments, which in addition to instruments with end effectors also comprise endoscopes and medical apparatuses to be operated, have a coupling interface which may be designed as a coupling unit and is also referred to as sterile unit. The apparatus for robot-assisted surgery further has at least one manipulator arm, at the proximal end of which the coupling unit is provided, to which the sterile unit is connectable in order to enable the mechanical, electrical and/or optical coupling between the manipulator arm and the surgical instrument.